your not leaking oil, that is oil releasing from the head b/c of pressure buildup. If you put the hose on then that oil will go to your intake and get burned up. That way is fine as well.
Are you not aware that tanks with holes in the BOTTOM will tend to leak? And that it doesn't matter whether the tank is overfilled or nearly empty, if the hole is in the BOTTOM, the fluid will drain out? Have you considered plugging the hole or getting a new tank??!!!!